The present invention relates to seats for use in motor vehicles, especially frames for bench-style school bus seats.
Recent federal safety standards mandate that conventional bench style seats as commonly found on most school buses be provided with suitable restraining systems such as seat belts or integrated lap/shoulder belts. In addition, they further mandate that the back rests of these seats give by a certain amount when impacted by a force exceeding a predetermined magnitude. In addition, they further mandate that these seats be rigid enough so that, when involved in a crash, they will keep a passenger sitting in the seat upright without any portion of the frame breaking or coming apart. See, for example, Federal Motor Vehicle Safety Standards (FMVSS) 222 and 210 (49 CFR xc2xa7xc2xa7571.210 and 571.222), which are incorporated by reference herein.
Current technology for designing crash resistant seating focuses on automobile and/or airplane seats. This technology has limited relevance to school bus seating where luxury and comfort are less important while simplicity and cost savings are more important.
Accordingly, it is an object of the present invention to provide a new crash resistant seat for use in a school bus or other vehicle which not only provides excellent crash resistance but also is simple and inexpensive to build.
This and other objects are accomplished by the present invention in accordance with which the frame of a crash-resistant seat is designed to undergo plastic flow or analogous phenomenon when an impact is applied to the back rest portion of the seat. In addition, one or more stopping mechanisms are provided in the seat frame to retard movement of the back rest farther than a predetermined limit. With this design, the back rest will move or xe2x80x9cgivexe2x80x9d a suitable amount when hit from the rear by an unrestrained child, with at least a portion of the energy from this impact being absorbed by plastic flow of the frame or analogous phenomenon. Once the predetermined limit to this movement is reached, however, the stopping mechanism(s) cause the back rest to become essentially rigid with the seat, thereby retarding further movement of the back rest and hence keeping any passenger in the seat generally upright and safe.
Accordingly, the present invention provides a shock absorbing frame for making a crash-resistant vehicle seat, as well as a vehicle seat made from this frame, the frame being composed of a seat member and a back rest arranged at a first seating angle with respect to the seat member, the back rest being adapted to bend forward to a second seating angle upon application of an impact force of a predetermined magnitude to the back rest, an energy-absorbing part of the frame absorbing at least a portion of the impact force as the back rest moves from the first to second seating angles, the frame further including at least one stopping mechanism designed to make the back rest essentially rigid with respect to the seat member when the back rest reaches the second seating angle thereby keeping a passenger sitting in the vehicle seat substantially upright in his seat as a result of a crash.
Preferably, the inventive frame is made from simple readily-available, off-the-shelf steel tube and sheet stock and hence is simple in design and inexpensive to build.